I've started writing up the design of power supplies in my costume project. When I say 'power supply' I don't mean anything as exotic as designing a linear regulator out of parts or designing a 300KV supply for a Tesla coil but instead a more pedestrian 'which chip do I pick and why?' sort of writeup. There are an absurd number of potential voltage sources out there - more than enough to get confused. The writeup focuses on the criteria you would use to select a voltage regulator and discusses the differences between linear and switching regulators before discussing the reasons for choosing regulator I did. You can read it here.